Pneumatic hammer.



No. 747,751. y PATBNTBD 17110.22, 1903.

' y A. c. MURPHY.'

PN-BUMATIG HAMMER.

APPLICATION FILED HAITI, 1901.l

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Patented December 22, 1903.

UNITED STATES l' PATENT OFFICE.

ALBERT C. MURPHY, OF EAST ST. LOUIS, ILLINOIS, ASSIGNOR TO STANDARD RAILWAY EQUIPMENT COMPANY, A CORPORATION OF ILLINOIS.

PNEUMATIC HAMMER.-

SPECIFICATION forming part of Letters :Patent No. 747,751, dated December 22, 1903.

Application filed May 17, 1901. Serial No. 60,693. (No model-l' To all whom/-zit mayconcer/'11,:

Be it known that I', ALBERT C. MURPHY, a citizen of the United States, anda resident of the city of East St. Louis, county of St. Olair, and State of Illinois, have invented certain new and useful Improvements in Pneumatic Hammers, of which vthe following is a speciication.

My invention relates to pneumatic hamxo mers, and has for its principalobjects to increase the force of the blow and to minimize shock and vibration.' It consists in the construction and arrangements of partshereinafter described and claimed. t5 In the accompanying drawings,which form,` part of this specification, and wherein Vlike symbols refer to like parts wherever they occur, Figure 1 is a longitudinal sectional view of my hammer with the piston inits rearward zo position. Fig. 2 is a longitudinal sectional view thereof with the piston in its forward position. Fig. 3 is a'detail View of the piston. Figa 4 is a longitudinal sectional view of the valve-block. Fig. 5 is a view'of the z5 rear end of the valve-block. Fig. 6 is a view of the front end of the valve-block. Figs.` 7,

8, and 9 are cross-sectional views of the valveblock on the lines 7 7, 88, and 9 9, respectively, of Fig. 4. Fig. 10 is a cross section 3o of the end plate; and Figs. 1l and 12 are views ot' the rear and front sides thereof, re-

f spectively. Fig. 13 is a detail of the valve.

'lhe principal elements of the present construction are a cylinder' 1, a piston Z therein,

a valve-block 3, and a valve4 therein, and a handle 5, all assembled in the general inanner common in tools of this kind".Y The' front end of the cylinder is open, and its` nose is adapted for the reception of the shank ot' a chisel or other tool 6. The rear end of the cylinder is closed by a plate '7, interposed between the cylinder andthe valve-block. The valve-block is a cylindrical piece having a cylindrical bore arrangedy axially, the front end of said bore being of larger diameter than the rear portion thereof. The valve is a cylindrical plug whose front portion is of larger diameter than the rear portion, the two portions being made to tit and slide in 5o thecorresponding portions of the Valve-block.

The handle portion comprises a grasping- `socket-piece 9.

lthrough said handle into the socket' portion,

and thence into a chamber'14, formed in the .rear end of the valve-block, whereby the rear end-of the valve is exposed at all times to the pressure from the source of supply.

From the chamber 14 in the rear of the val ve-block a` passage-way 15 extends forward through said valve-block to a point close to the front end thereof, and thence inwardly, 7o 'and opens through asmall port 16 into the -bore of` said valve-block in position to be covered by the valve in its forward position, but

to be uncovered' when the valve is in its rearward position. Another small port l7, which g lopens into the boreof the valve-block inthe same annular plane as the port 16, connects with a passage way 18, extending from 'the front end of thevalve-block and opening through a portl9 into the smaller bore of the 8o valve-block, said port 19 being in position to bel covered bv the smaller diameter of the valve when the valveis in its rearward position and to bein register with a groove 20 in said valve when the valve is in itsforward position. Back of said last-mentioned port. 19 is a port 21, which opens into the smaller bore of the'valve-block vand communicates with a assage-wa l22 extendiirr radiall' I) o y 7 :s .l

through the valve-block andcornmunicatng 9o with the space surrounding the valve-block, which space is periiianentlyopeu to the atmosphere through the exhaust-port 23 in the. socket-piece of the handle. This last-inentio'ned port 2l is in position to register With 95 the groove 20 of the valve in `all positions of the valve. Back of this last-mentioned port 2l and near the endjof the valve-block is an annular groove 24 in the small bore ot' thevalveblock. The annular groove 24 is in toc. position to register with the groove 2O of the valve when the valve is in its rearward position and to be uncovered by the end of the valve when the valve is in its forward position. This groove 24 comm unicates with a passage-way 25, extending forwardly through the valve-block and the end plate and opening into the rear end of the cylinder, whereby when the valve is in its forward position the pressure is supplied directly from the source of pressure and through the chamber 14 in the rear of the valve-block, thence to said annular' groove 24, and thence through the passage-way 25 to the rear end of the cylinder.

Extending from the chamber 14 in the rear end of the valve-block is a passage-way 26, which extends forwardly through said valveblock and the plate 7 and the wall of the cylinder and opens into the cylinder through a port 27 at a point directly behind the rear end of the piston when the piston is in its extreme forward position. In the same annular plane with this port 27 is a second port 2S, which opens into a passage-Way 29 in the wall of the cylinder, which communicates with a port 30 in the front side of the plate 7. This port 30 opens into a passage-way 31, extending radially through said plate to the center thereof and thence opens through a port 32 in the rear side of said plate. The piston is provided with a circumferential groove 33 nearits rear end, whereby the ports 27 and 28 are brought into communication with each other when the piston approaches the limit of its forward stroke. When the groove 33 thus registers with the two ports 27 28,1ive air is ad mitted through the passageway 26, port 27, groove 33, port 28, passageways 29 and 31 into the valve-chamberimm ediately backof the plate. The area of the front end ofthe valve being larger than the area of the rear end the valve is forced backwardly, whereby the valve covers the groove 24 in the valve-block, and thereby cuts off the live air from the rear end of the cylinder-chamber. During the forward movement of the piston the front end of the cylinder is exhausted through a port 34 near the forward end of the chamber, which port communicates with a passage-way 18, extending back through the wall of the cylinder and the head-block, and communicating with the passage-way 18, which opens through the port 19 into the valvechamber opposite the groove 20 in the valve, and thence through the passage-way 22 directly to the atmosphere. When the Valve is moved to its rearward position, as hereinbefore described, live airis admitted through the passage-way 15 and its port 16 in front of said valve, and thence through the port 17 into the passage-way 18, which leads to the port 34 at the forward end of the cylinder, the other port 19 of said passage-Way 18 being at the same time closed by the valve in its rearward position. The piston is thus forced backwardly by the live air ad mitted in frontof it. At the same time the rear end of the cylinder is exhausted through the passage-way 25, extending through the plate and terminating in the circumferential groove 24 in the valve-block,\vhich groove in the rearward position of the valve is in register with the groove 2O of the valve, and thereby in communication with the exhaust-port 21, which communicates directly with the atmosphere.

In addition to the regular exhaust passageway 22 I provide a supplemental exhaustpassage 35, having a port 3b' opening into the cylinder at a point in position to be covered by the piston when it has traveled about onethird of its stroke. This port communicates with the passage way 35, which extends through the wall of the cylinderand the plate and the valve-block, and opensinto the space surrounding said valve-block at a port 37. rlhe port 37 is permanently in communication with the atmosphere.

The front end of the cylinder has a shoulder 38 to prevent the accidental coming out of the piston, and the piston is reduced at its forward end, so as to clear the shoulder in delivering its blow to the tool.

In case the piston should make an abnormal stroke by reason of the withdrawal ofthe tool it is held in its forward position by means of pressure admitted -in the rear Athereof through the port-27, which communicates permanent ly with the source of pressure through the passage-way 26. "lhe main admission and exhaust port 34 for the front end of the cylinder is covered bythe pistou in such abnormal position. In order to prevent the movement of the piston from this position, the passage-way 29 is provided with a port 39, opening into the cylinder in the same plane as the port 36 of the exhaust-passage By this arrangement the groove 33 of the piston will register with both the ports3t and 39 when the piston is abnormally ad vanced, and therefore the pressure admitted through port 27 into the cylinder-chamber will escape through port 28, passageway 29, port 39, pistongroove 33, port 36, and passage-way 35 in sufficient quantity to permit the rapid reciprocation ol the valve without affecting the movement of the piston. The space back of the shoulder of the Valve is open to the atmosphere through a relief-passage 40 specially provided therefor. In order to prevent the violent impact of the valve against the plate 7, which constitutes the front wall ot' the valve-cham ber,it is preferable to form socketholes 43 in the rear side of said plate. The valve-block is provided with dowel-holes 41 44 45 for assembling the parts in proper position.

The operation of this construction is as follows: When the valve and piston are in the positions shown in Fig. 1, tho piston is at the limit of its rearward stroke and the Valve has shifted so as to admit pressure to the rear end ot' thepiston-chamher. In this condition pressure is admitted through the su pply-duct 13, chamber 14 in the rear ot' the valve-groove 24, and passage-way 25, d1 reci ly into the rear end of the piston -chamber.

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The front end of the piston-chamber is open to the atmosphere throughA the port 36, passage-way 35, and port 37, and also through the port 34, passage-way 18, port 19, valvegroove 20, port 21, and exhaust-port 22, and consequently the pressure on the rear end of the piston forces said pistonforwardlyto deliver its blow to the shank of the tool 6 in the fore end of the cylinder. Just before the piston reaches the forward limit of its stroke its groove 33 registers simultaneously with the port 27 of the passage 26, which is permanently connected to the supply-duct and.

with the port 28,which communicatesvthrough the passage-way 29 in the wall of the cylinder with the port 30 of the passage-way 31, arranged transversely inthe valve-plate and opening through the port 32 into the valvechamber in front of the larger end of. the valve. In thisposition of the piston pressure is admitted from the supply-duct through the ports, passage-ways, and groove just mentioned into lthe front end of the valvechamber, and said front end being of larger diameter vthan the rear end such pressure effects the backward movement of the valve into the position shown in Fig. 2. 1n this position the rear end of the valve cuts off the pressure from the rear end of the pistonchamber and at the same time brings the port 24, which is connected by the passageway 25 with the rear end of the piston-chamber, into register with the valve-groove 20, which val'vegroove also registers with the exhaust-port 21 and passage-way 22 and thence to the atmosphere. In this rearward position of the valve the front end of the vvalve has uncovered the port 16, which communicates through the passage v15 with the supply-duct, and therefore admits pressure iniothe front end of thepvalve-chamber directly from the sourceof supply. From the front end of the valve-chamber pressure is admitted through the passage-way 17, which has likewise been uncovered by the valve in its rearward movementinto the passage-way 18, and thence through the port 34 into the front end of the piston-chamber, the real-most port 19 of this passage 18 being closed by the valve in its rearward position. In this position, therefore, pressure is admitted to the front end of the cylinder through the front end'of the valve-chamber and the ports and passage-ways in communication therewith and is-exhausted from the rear end of the piston-chamber through the passage 25 and the groove of the valve and the exhaust-port. Consequently the piston is driven rearwardly. The first effect of the rearward movement of the piston is to carry the piston-groove out of register with the ports 27 and 28. As the piston continues to move rearwardly the front end of the valve-chamber is opened to exhaust by the piston uncovering the port 39 ofv the passage-way 29, which comm unicates.- with the front end of the valve-chamber by means of the passage-way 31 and port 32 of the valve-plate. This brings the front end of the valve-chamber into communication with the front end of the piston-chamber, and the frontend of the piston-chamber istat the same time opened to exhaust through the port 36, passage-way 35, and port 37, thereby bringing the front end of the 'valve-chamber into l communication with the atmosphere. The pressure being thus released in the front end gof the valve-chamber, thefpressure on the rear end of the valve-chamber forces the Valve forwardly into the position shown in Fig. 1, the piston meanwhile continuing its rearward movement tothe position also shown in Fig. 1. .The operation .above described is then repeated. In the real-most position of the piston pressure is admitted to the front end of the piston-chamber through the port 27, but is exhausted therefrom through the ports 34 and 36, so as inno way vto interfere with the forward vmovement of the piston.

rIt is noted that in the normal stroke of the port 27 into the rear end of the piston-chamber, tending to hold the piston in its abnormal position.l This pressure escapes partially through the port 28, passage-way 29, port 39, groove 33, port 36, passage-way 37 to the atmosphere; but part of such pressure passes through the port 28, passage-way 29, and passage 31 to the front end of the valve-cham-. ber in sufficient quantity to effect the back--` ward movemeutof the valve. The backward `movement of the valve has the effect of eX- hausting the rear end of the piston-chamber, and thereby relieving the pressure in the front end of the valve-chamber also, whereupon the valve is forced forwardly by the consta-nt pressure on its rear vend. The port 16, which is uncovered by the valve in ils backward movement, being small in compari-- son with the cylinder-ports, does not Yadmit sufficient pressure to prevent this operation of the valve. The valve thus continues to reciprocate so long as the pistou is in its abnormally-forward position.

What I claim 'as new, and desire to secure by Letters Patent, is-

1. Apneumatichammercomprisingacylinder having ports for the admission and release of air, a piston in said cylinder and a valve for controlling the admission and release of air, said valve being of the differential-piston type andhaving its smaller end exposed to constant pressure and having a groove in its smaller diameter arranged to 'communicate at all times with a main releaseport and to communicate alternately with the piston, and pressure is admitted through the IIO respective ends of the cylinder, the cylinder having a supplemental exhaust-port located in the forward portion thereof in position to be uncovered by the piston shortly before the completion of its return stroke, and said piston having also a port communicating with the larger end of the valve-chamber and arranged to be uncovered by the piston simultaneously with the supplemental exhaustport, substantially as described.

2. A pneumatic hammer comprisingacylinder having. ports for the admission and release of air, a piston in said cylinder and a valve for controlling the admission and release of air, said valve being of the differential-piston type and having its smaller end exposed to constant pressure and having a` groove in it-s smaller diameter arranged to commmunicate at all times with a main release-port and to communicate alternately with the respective ends of the cylinder, the cylinder having a supplemental exhaust-port permanently open to the atmosphere and located in the forward portion thereof in position to be uncovered by the piston shortly before the completion of its return stroke, and said piston having also a port communieating with the larger end of the valve-chamber and arranged to be uncovered by the piston simultaneously with the supplemental exhaust-port, substantially as described.

3. A pneumatic hammer comprising a liandle portion, a cylinder, a piston in said cylinder, a valve-block having ports for the admission and release of air, and a solid plugvalve of the differential-piston type for controlling the admission and release of air, said valve being located in a separate valve-chamber back of said cylinder and in alinement therewith and having a circumferential groove in its smaller portion, all arranged to cooperate, substantially as described.

4. A pneumatic hammer comprising a handle portion, a cylinder, a valve-block having ports for the admission and release of air, and a solid plug-valve of the differential-piston type for controlling the admission and release of air, one of said ports being in front of said valve and communicating through a passage-Way with the middle portion of said cylinder, said valve being in a separate valvechamber located back of said cylinder and having acircumferential groove in its smaller portion to cooperate with the main exhaustport, and having its larger diameter at the front end, substantially as described.

5. A pneumatic hammer comprising a handle, a cylinder, a piston therein having a groove near its rear end, a valve-block, a valve having a groove near its rear end, and ports and passage-ways for the admission and release of air, the rear end of the valve being of smaller diameter than the front end and exposed to constant pressure, the front end of the valve-chamber being provided with small ports in position to be covered and uncovered by said valve, and communicating respectively with the source of pressure and with the front end of the piston-chamber, The latter passage-way also opening into the valvechamber in position to register with the valvegroove when the valve is in its forward position, said hammer also being provided with passage-Ways opening into the piston-chamber at a point adapted to register with the groove in the piston when the piston is in its normal forward position, one of said passageways being connected to the source of pressure, and the other of said passage-Ways being connected to the front end of the valvechamber, and said ham mer having a passageway extending from the rear end of the piston-chamber into the valve-chamber at a point adapted to be traversed by the rear rib of the valve, and an exhaust-port in register at all times with the groove in said valve, substantially as described.

6. A pneumatic hammercomprising a handle, a cylinder, a piston therein having a groove near its rear end, a valve-block, a valve having a groove near its rear end, and ports and passage-Ways for the admission and release of air, the'rear end of the valve being of smaller diameter than the frontend and exposed to constant pressure, the front end of the valve-chamber being provided With small ports in the same annular plane in position to be covered and uncovered by said valve, and communicating respectively with the source of pressure and with the front end of the piston-chamber, the latter passage Way also opening into the valvechamber in position to register with the valvegroove when the valve is in its forward position, said hammer also being provided with passage-ways opening into the piston-chamber at a point adapted to register with the groove in the piston when the piston is in its normal forward position, one of said passage- Ways being connected to the source of pressure, and the other of said passage-Ways being connected tothe front end of the valvechamber, and said hammer having a passageway extending from the rear end ol the piston-chamber into the valve-chamber yat a point adapted to be traversed by the rear rib of the valve, and an exhaust-port iu register at all times with the groove in said valve, substantially as described. u

7. A pneumatic hammer comprisi nga cylinder, a piston therein, a handle having a socket therein, and a hollow cylindrical valve-block in said socket arranged to form a chamberI at the rear of said valve-block in communication with the source of pressure and with the rear end of the bore of the valve-block, a differential valve in the bore of the valve-block having its large area in the front end of the valve-block, a plate between the cylinder and valve-block constituting the front wall of the valve-chamber, said plate having a port opening into said valve-chamber and communieating with the source of pressure through passage-ways and porls controlled by the piston, substantially as described.

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ing into said valve-chamber and communieating with a port in the wall of the cylinder in position to register with a groove in the rear portion of the piston when the piston is in its forward position, said hammer also having a passage-way communicating with the source of pressure and having a port in `the wall of the cylinder arranged to register with said piston-groove simultaneously with said last mentioned port, lsubstantially as described.

9. A pneumatic ham mer comprising a cylinder, a pistou therein, a handle having a socket therein, and a hollow cylindrical valve-block in said socket-arranged to form a chamber at the rear of said valve-block in lcommunication with the source of pressure and with the rear end of the bore ofthe valve-block, a differential valve in the bore of the valve-block having its large area in the front endof the valve-block, a plate between the cylinder and valve-block constituting the front wall of the 10. A pneumatic hammer comprising a cylinder, a handle having a socket therein, and a hollow cylindrical valveblock vin said socket, a valve in the bore of the valve-block,

Aand a plate between the cylinder and valveblock constituting the front end of the valvechamber, said plate having sm all socket-'holes therein adapted to cushion the valve, subsiantially as described.

l1. A pneumatic hammer comprising a cylinder, a piston therein, a handle having a socket therein, and a hollow cylindrical valveblock in said socket arranged to form a chamber at the rear of said valve-block in communication with the source of pressure and with the rear end of the bore of the valveblock, a differential Valve inthe bore of the valve-block having its large area in the front end of the valve-block, and a plate between the cylinder and valve-block constituting the front lwall of the Valve-chamber, said valve having a groove near its rear end, and said block having an exhaust-port always in register with said groove, and a passage-Way opening into the valve-block in position to be traversed by the rear end of the kvalve and communicating directly with the rear end of the pistonchamber,and said valve-block having also a passage-way communicating with the source of pressure and opening through a small port into the valve-chamber in position to be covered and uncovered by the front end of the valve,and said valve-block having a passage-way' opening into the front end of the cylinder, and having two openings into the bore of the valve-block, one of said openings being opposite the small opening hereinbefore mentioned, and the other opening being in position to register withl the groove in the valve when the valve is in its forward position, substantially as described.

St. Louis, Missouri, May 15, 1901.A

A. o. MURPHY. 

